The subject matter disclosed herein relates generally to joining together a leading edge of a newly prepared web from a new roll of material to a trailing edge of a web from an expiring roll of material that is being fed to a continuous web processing operation and, more particularly, to an apparatus and methods for forming a butt splice to join the webs using a UV-cured liquid adhesive applied within a gap formed between the leading edge of the web from the new roll of material and the trailing edge of the web from the expiring roll of material.
Various apparatus and methods for joining or splicing webs used in continuous web processing operations are known in the art. One common method of joining web materials is a lap splice, wherein a leading edge of a new web is treated with a suitable adhesive, and at a proper time is manually lapped over a trailing edge of an expiring roll. U.S. Pat. No. 4,519,858 describes an apparatus and method for making such lap splices. Drawbacks to the lap splice include an undesirable double thickness of material at the splice, which is particularly unsuitable for relatively thick web materials. Further, because of restrictive operations downstream of the splice, certain types of materials, including two-ply pressure sensitive label stock, cannot be spliced in a lap splice.
Another common method of joining webs is through the use of a butt splice. With a butt splice, the leading edge of the new roll is butted up against, but does not overlap, the trailing edge of the expiring roll. A relatively thin, single-sided piece of adhesive tape is then used to join the butted ends together. In the past, hand operations have had to be used to achieve a good-quality butt splice. Typically, a good quality butt splice has less than a one/one thirty-second inch gap between the butted ends of the webs that are being joined. The accuracy required has necessitated the stoppage of the running web from the expiring roll for a sufficient time to make a hand splice. However, as each roll expires, such stoppage results in significant loss of production time. More recently, automated machines and methods have been developed to quickly and accurately join webs through the use of an adhesive tape to form the butt splice. See, for example, U.S. Pat. No. 7,022,205. However, in some conventional butt splicing machines and methods, the adhesive tape undesirably increases a thickness of the splice. Moreover, the adhesive tape may not adequately adhere to certain web materials, such as web materials coated with grease-proof, water-proof, or vapor deposition coatings, for example.